Water cooled furnace



Feb. 7, 1933. w. ARMACQST 1,896,273

WATER COOLED FURNACE Filed Oct. 9, 1930 INVENTOR Wilbur HAv'ma/costORNEY Patented Feb. 7, 1933 l UNITED STATES PATENT, (is-me wILBun n.ARMACOST, or NEW YORK, n. Y., ASSIGNOR 'ro THESUPERHEATER com PANY, onNEW YORK, N. Y.

WATER COOLED FURNACE Application filed October 9, 1930. Serial No.487,490

My invention relates to water cooled furnaces-and more particularly tothose having surfaces on which the centers of the water tubes are spacedapart a sufficient distance so thatslagging of the inner face oftherefractory wall of the furnace wouldoccurin the ordinary forms ofconstruction, and aimsto provide an arrangement whereby widespacingiof-the tubes may be retained and the slagging prevented. 7 Q gIn order that my invention may be fully understood, I will describe indetail, in con-' nection with the attached drawing, one of several formsof boiler furnaces in which my invention may be embodied. In said draw-Fig. 1 is a vertical sectional view through a boiler furnace having awall section in accordance with my invention; Fig. 2 is a fragmentaryelevation of a portion of the wall of the furnace shown in Fig. 1, andFig. .3 is an enlarged sectional View on line of Fig. 1.

Present-day boiler practice tends more and more to operation of theboilers at high ratings, with the-result that higher and higher amountsof fuel per cubic foot of combustion space have been employed. At onetime, the gradual increase in outputs of boilers and furnaces wasstopped by the serious slagging of the furnace refractories caused byparticles of molten ash striking the face of the furnace wall. Thedifliculties with the refractories have been largely overcome by liningthe furnace with water tubes whereby the refractories are protected to agreat extent from the furnace temperatures. On certain surfaces ofboiler furnaces, however, it is desired to space the centers of thewater tubes so far apart that, unless special precautions are taken,slagging of the furnace refractories would occur in certain types ofboiler furnaces now in use. For instance, it is convenient often tointroduce pulverized fuel into the boiler furnace through burner 11ozzles which project into the furnace through the walls thereof at pointsbetween the water tubes. This arrangement of the burners necessitatesspacing the water tubes far enough apart so that, when using pulverizedfuel in accordance with most recent practice,

occur. I have found, however, that the water tubes can be spaced farenough apart along the inner face of, the .furnace wall topermitintroduction of burner nozzles for pulverized fuel without materialslagging of the refracslagging of the furnace refractoriesis apt to toryprovided the water cooled surface. is

built out a sufiicient distance from the wall of the furnace.- Thenecessary thickness of water wall for this purpose depends upon thefusing point of the ash of the coal, but withash of an averagefusingpoint the maximum thickness of the water wall perpendicular to thefurnace wall is abouttwice the minimrun width of the openings in thewater wall measured parallel to the furnace wall. Moreover, it will beunderstood that, while having special advantages in furnaces havingburner nozzles projecting between adjacent water wall tubes, myinvention is not limited to furnaces using pulverized or liquid fuel asit may be desired at times to space the refractory protecting watertubes widely for other reasons. I

' Referring to the drawing, the installation illustrated thereincomprises a furnace chamber 10 having refractory lined walls 12,12

which are protected from slagging by closely spaced water tubesltarranged in a'single layer along the inner face of the refractory. Overcertain wall sections 12a of the furnace 10, however, it'is desired tospace the refrac-v tory protecting tubes so far apart that-slag ging'would occur with only I one layer of tubes. As illustrated, along thewall section epreferto make the anti-slagging means of two layers ofwater tubes 14a and 14b, each tube of one layer united atits' endsto oneof the other layers andflto'common throats l l'c such wall, but I do notlimit myself to through which the tubes 14a and 14b connect to headers18 and 20. The tubes in the layer 14?) extend inwardly into the furnacefar enough from the surface of the refractory to shade the exposedsurface of the refractory sufliciently to prevent itfrom substantialslagging even when the furnace 10 is being forced with pulverized fuel.As illustrated, the elements of tubes in layer 14?) farthest from therefractory lie about twice as far from the refractory as the minimumopen distance between adjacent tubes in layer 14a.

The arrangement illustrated and in which water tubes are connected inpairs to common throats is commonly referred to as a bifurcatedarrangement. It will be under stood that I do not limit myself tobifurcated tubes. Moreover, as illustrated, the tubes in layer 14?) arearranged so that their projections on the surface of wall 12a coincidewith the projections of the tubes of layer 14a on such relativearrangement. I

In Fig. 1, I have shown furnace chamber 10 as associated with a boiler22 of'afiwell known type, but it will be understood that the boiler isnot a part of my invention. 7

I claim: 2

1. The combination of a furnace chamber having an arch portion at itsupper end, an inner layer of protecting water tubes over said archportion, and an outer layer of protecting tubes over said arch portion,the tubes of said inner layer being spaced apart a distance to causeslagging of the refractory when the furnace is operated at high ratings,the tubes invsaid outer layer having an arrange ment suchthat theprojected area of each such tube upon the refractory surface of the archoverlaps the projected area upon such surface of one of the tubes of theinner layer, each pair of said overlapping tubes being sufficientlyclose to adjacent pairs to shade the refractory surface to preventslagging thereof at the maximum rating for which a furnace is designedbut regularly spaced from adjacent pairs to permit a direct view of thesurface of the refractory to the extent tory surface overlaps theprojected area upon such surface of one of the tubes of the inner layer,each pair of said overlapping tubes being suflicientely close toadjacent pairs to shade the refractory surface to prevent slaggingthereof at the maximum rating for which the furnace is designed andregularly spaced from adjacent pairs to permit a direct view of thesurface of the refractory, whereby a portion of the refractory surfaceof the arch may reach a temperature adapted to promote combustion in thefurnace.

3. The combination of a furnace chamber having a wall having an archportion at its upper end alongside of which is a layer of protectingwater tubes spaced apart a distance suflicient to cause slagging of therefractory when the furnace is operated at high ratings, a second layerof'spaced water tubes farther from the refractory surface than saidfirst layer and each tube of which has an arrangement such that itsprojected area on the refractory surface overlaps the projected area onsuch surface of one of the tubes ofcsaid first layer,'each pair .of saidoverlapping tubes being sufiiciently close to adjacent pairs to shadethe refractory surface to prevent slagging thereof at the maximum ratingfor which the furnace is designed but regularly spacedfrom adjacentpairs to permit a direct view of the surface of the refractory, and aburner arranged to deliver into said furnace between adjacent pairs ofsaid overlapping tubes.

4. The combination as set forth in claim 1 together With a burnerarranged to deliver into the furnace through the arch portion andbetween'adjacent pairs of overlapping tubes. j i j WILBUR H. ARMACOST.

whereby a portion of the refractory surface of the arch may reach atemperature adapted to promote combustion in the furnace.

2. The combination of a furnace chamber having a wall having an archportion at its upper end, a layer of closely spaced protecting watertubes over said wall below said arch, and a double layer of protectingwater tubes over said arch portion, tubes of the inner layer over saidarch portion being spaced apart a distance to cause slagging of therefractory when the furnace is operated at high ratings, the tubes inthe second layer over said arch being spaced farther from Y therefractory surface than said first layer and having an arrangement suchthat the projected area of each such tube upon the refrac-

